In performing biometrics authentication, there are used blood vessels as a subject to be authenticated. There has been proposed, as an authentication apparatus using blood vessels as a subject to be authenticated, an apparatus that uses parameters obtained by Hough-transforming digitized image data obtained as a result of imaging a finger as registration data or data to be collated with registration data (refer to, e.g., Patent Document 1).
This authentication apparatus focuses on the fact that the blood vessels in the image have high linearity and adopts a Hough transform scheme capable of quantifying a linear component dominating in the image as parameters, thereby reducing redundant information, as well as improving authentication accuracy.    Patent Document 1: Jpn. Pat. Appln. Laid-Open Publication No. 2005-115615
However, in such an authentication apparatus, in the case where the amount of a blood vessel component in image data obtained as an imaging result is small or amount of a noise component in the image data is substantially large, even if data obtained by performing Hough transform for the image data is used as registration data or data to be collated with registration data, characteristics of the Hough transform are not sufficiently reflected in the authentication processing, resulting in a decrease in the authentication accuracy.
On the other hand, in recent years, a compact construction has been desired for the authentication apparatus and, in view of the downsizing, the apparatus preferably has a simple structure.